Sea Mountain (Seamount)

A seamount is an isolated submarine volcanic mountain that rises at least 1,000 m from the seafloor without reaching the surface; smaller rises are termed knolls or abyssal hills. Most are extinct hot-spot or ridge-flank volcanoes with steep basaltic flanks. Their summits force deep water upward, so they raise local biological productivity and are managed as fishing and conservation areas. Tens of thousands have been mapped, and a flat-topped, wave-truncated one is a guyot. Seamounts are navigation hazards where charted depths are sparse: an uncharted shoaling summit caused the USS San Francisco grounding in 2005.